1. FINGERPRINT ANALYSIS

2. History/Field
1823: description of fingerprint types is published by Czech physiologist, Jan Evangelist Purkyn
1858: England is the first country to use fingerprints as a system of criminal identification
1903: Leavenworth Federal Penitentiary received a prisoner by the name of Will West who had almost the same Bertillon measurements (as well as appearance) as another prisoner currently serving a life sentence for murder; this case ended the use of Bertillon measurements

3. History/Field (cont.)
1975: the FBI introduces the Automated Fingerprint Identification System (AFIS)
Dactyloscopy is the study of fingerprint identification
Fingerprint Examiners are responsible for examining fingerprints

4. What is a fingerprint?
Skin is composed of two layers: an outer layer called the epidermis
and an inner layer called
the dermis
The dermis has ridges,
called dermal papillae,
that project upward into
the epidermis to provide
friction when picking up
an object
The dermis contains sweat and oil glands

5. What is a fingerprint? (cont.)
The perspiration, oil, and salts from these glands leave a residue conforming to the pattern of the dermal papillae
The impression left behind is called a fingerprint
The papillae form during fetal life (10th week) and are unique to every individual; even twins have unique fingerprints

6. Types of Prints
There are 3 types of prints that investigators look for at crime scenes:
Patent fingerprints—visible prints transferred onto smooth surfaces by blood or other liquids
Plastic fingerprints—indentations left in soft materials such as clay or wax
Latent fingerprints—made visible by dusting with powders or the use of chemicals

7. Collecting Fingerprints
There are two methods for collecting fingerprints:
Dusting
Chemical Fixation

8. Dusting
Hard surfaces such as glass yield prints when lightly dusted with powder
The powder can be brushed in place with either a camel-hair or fiberglass brush
Care must be taken so as not to brush the print away or add too much powder so that the space between the ridges is filled
Tape can then be used to “lift” the print

9. Chemical Fixation
SuperGlue—heated SuperGlue will adhere to non- porous substances such as leather or plastic
Ninhydrin—reacts with prints to form a blue- purple color; usually used to lift prints off of paper
Iodine—iodine crystals or heated iodine will produce a purple vapor that will make prints visible but the print will fade so it must be photographed
Silver nitrate—reacts with print so that it can be seen under ultraviolet light

10. Fingerprint Patterns There are 3 main fingerprint patterns
These patterns are determined by using deltas
A delta is a “Y” pattern formed by the divergence of ridges
Forensic examiners also look at the Core , which is the center of a whorl or loop, and Ridge count, which is counting from the core to the edge of the delta and distinguishes one fingerprint from another

11. Example of Core and Delta

12. Fingerprint Patterns (cont.)
The patterns are:
Loops: found in 65% of the population and contain one delta
Whorls: found in 30% of the population and contain 2 or more deltas
Arches: found in 5% of the population and have no deltas

13. Loops
A loop pattern has one or more ridges entering from one side, curving, and then leaving the same side from which it began
Loop can be identified as being either an ulnar loop or a radial loop
Ulnar loops open away from the thumb
Radial loops open toward the thumb
Blue Box is Delta

14. Ulnar and Radial Loops (right hand)

15. Whorls Contain 2 deltas and there are several subgroups:
Plain whorl: has two symmetric deltas and a complete circuit; if an imaginary line is drawn between the two deltas, it will touch or cut one of the recurving ridges
Blue Boxes are Deltas

16. Plain whorls

17. Whorls (cont.)
Central Pocket Whorl: has two deltas and a complete ridge circuit; the deltas are not symmetric and one side appears to be stretched like elastic; an imaginary line drawn between the deltas will not cross the inner pattern;
found in 2% of the
population
Blue Boxes are Deltas
Green circle shows complete circuit

18. Central Pocket Whorls

19. Whorls (cont.)
Double Loop Whorl: has two loops and two deltas; found in 4% of the population
Blue Boxes are Deltas

20. Double Loop Whorls

21. Whorls (cont.)
Accidental Whorl: consists of a combination of two different types of patterns, with the exception of the plain arch; it contains two or more deltas; it is a pattern which possesses some of the requirements for two or more different types, or a pattern which conforms to none of the definitions; found in 0.01% of the population
Blue Boxes are Deltas

22. Accidental Whorls

23. Arches
Ridges that enter on one side of the finger and cross to the other side while rising upward in the middle
There are 2 subgroups of arches:
Plain arch: the ridges move from one side of the print to the other with no significant changes; found in 4% of the population
Tented arch: arch that appears to have a spike acting as a pole in the middle; found in 1% of the population

24. Plain Arches

25. Tented Arches

26. Identify each fingerprint pattern.?
DOUBLE LOOP WHORL
PLAIN WHORL A B
RADIAL LOOP
Right Hand
Left Hand
TENTED ARCH
PLAIN ARCH C
Right Hand E D
Right Hand
Left Hand

27. Example of a Ten Card
The Ten Card contains both rolled and plain fingerprints

28. Individual Ridge Characteristics
Use these characteristics as points of identification when comparing fingerprint samples. The more points you can find in common, the better the match!

29. Ridge Characteristics
Crossover
Core
Bifurcation (fork)
Ridge ending
Island
Delta
Pore
Scar
EXAMPLE

30. Practice
ames/fingerprint/index.html